Refrigerating apparatus



N6v. 12, 1940. v

F. F. STARR REFRIGERATING APPARATUS ori i al Filed M31, 1935 Patented Nov. 12, 1940 UNITED STATES PATENT OFFICE REFRIGERATING APPARATUS tion of Delaware Application May 31, 1935, Serial No. 24,263 Renewed December '7, 1938 9 Claims.

This invention relates to refrigerating apparatus and more particularly to controlling means for the refrigerant circuit of a compression refrigerating machine, In refrigerating apparatus of the compression type designed for low cost, it is essential, if satisfactory operation is to be secured, that the refrigerating cycle takes place with maximum efficiency at all times since with a low powered motor, which cost limitations. im-

10 pose, the unit must be operated as near as possible to its theoretical maximum efliciency if satisfactory box temperature and ice freezing characteristics are to be maintained.

It has been possible heretofore to construct low cost refrigerating apparatus which will operate with satisfactory efliciency at full load by proper design of the system and proper correlation of the relative capacities of its various elements. Many such low cost systems employ a fixed restrictor to regulate expansion of the refrigerant in order to take advantage of the low cost and freedom from service difficulties inherent in that type of expansion device. However, the natural characteristics of a fixed restrictor are such that the changes in rate of flow therethrough produced with changes in pressure differential across the same do not produce the optimum flow rates for all possible load conditions. It has been necessary in designing a system of this character,

therefore, to choose some one load condition, usually the maximum, under which the system is designed to operate at maximum efficiency and to accept operation at considerably less efilciency under all other load conditions.

If a refrigerating apparatus of the character described is designed to operate at maximum efficiency under maximum load conditions, such, for example, as a high room temperature, together with a large freezing load of water to be cooled and frozen,the considerably reduced efliciency under less than full load conditions causes unnecessarily large current consumption at times when the apparatus is not operating under maximum load.

'Heretofore, it has been possible to reduce the high current consumption at partial loads only by sacrificing efficiency at full load, and it is an object of the present invention to provide a mechanical refrigerating apparatus which is designed to operate at maximum efficiency under full load, and in which the loss of efficiency and consequent current consumption are materially reduced when operating under partial load conditions.

In order to meet these requirements, the present invention provides, in addition to the usual fixed restrictor or other control device which regulates the expansion of liquid refrigerant into the evaporator, an additional restricting means located at the outlet of the condenser for the purpose of reducing the restriction during oper- 5 ation at part load and insuring that the refrigerant delivered from the condenser will be substantially all in liquid form under full load. This is particularly advantageous in systems utilizing a heat interchanger for improved efficiency at full 10 load, but in which the interchanger introduces a substantial loss of energy when the refrigerant entering the same has not been completely liquefied as happens under full load operation.

It is a further object, therefore, to provide 15 means at the outlet of the condenser in a refrigerating apparatus for preventing the passage of gaseous refrigerant, particularly in a refrigerating apparatus employing a heat interchanger for equalizing temperatures between the liquid re-- s.

. frigerant entering the evaporator and the gaseous refrigerant leaving the same. It is preferred to employ a restrictor for this purpose which has a variable resistance together with automatic means for varying its resistance in response to tempera- 5i ture conditions. Further objects and advantages of the present invention will be apparent from the following description, reference being had to the accompanying drawing wherein a preferred form of the 30 present invention is clearly shown. In the drawing, the figure illustrates diagrammatically a refrigerating system embodying the present invention showing portions of the system in cross section and on a larger scale. 35

The refrigerating system includes a motorcompressor unit II] which delivers compressed refrigerant through a conduit l2 to a condenser M where the refrigerant is liquefied and passes to a variable restrictor device I 6. From the re- 40 strictor IS, the refrigerant passes to a heat in-- terchanger l8 for exchanging heat between the warm liquid refrigerant and the cold gaseous refrigerant and then passes through a conduit 20 to a fixed restrictor 22 The refrigerant expands from the restrictor .22 into an evaporator 24, whence it passes by a conduit 26 to the interchanger l8 and thence to the compressor Ill. Suitable automatic switch means 21 are provided for stopping and starting the motor-compressor 50 unit in response to the temperature conditions at the evaporator. The evaporator 21 is preferably located within a compartment to be cooled indicated by the dotted line 28, while the condenser H is exposed to the air outside the compartment thus opens the entrance to the passage 38.

28. The heat interchanger l8 and the restrictor ii are preferably also located outside the compartment 28. i

The restrictor l6 comprises a body member 5 formed of a cylindrical shell 30 having an end closure 32 provided with an inlet connection and an end closure 34 provided with an outlet connection. The member 34 contains a passage 36 of fixed dimensions which is calibrated to offer 10 some degree of resistance to the passage of refrigerant therethrough. A second fixed dimension resistance passage 38 is also formed in the end closure 34. Within the body member 30 there is mounted a valve member 40 for controI- ling the inlet to the passage 38. The valve 40 is operated by a thermally responsive rod 42. The rod 42 is formed of a material having a higher coefficient of expansion than the material of the shell 30, for example, the rod 42 may be formed of copper and the shell 30 may be formed-of steel.

In operation of the device under maximum load conditions, .for example, when the temperature of the air outside the compartment 28 is high, the head pressure in the condenser I 4 will be high and the calibration of the restrictor 22 is such that with this high head pressure, too much refrigerant would pass to the evaporator 24. Under these conditions, the refrigerant within the body -of the restrictor I6 is warm and the copper 80 rod 42 expands to close the valve 40, thus forcing all of the refrigerant to pass through the restriction 36. Under these conditions, additional restriction is imposed between the condenser and the evaporator which reduces the rate of flow 35 to the proper value. Under conditions when the apparatus is not operating at maximum load, such as for example, when the temperature outside the compartment 28 is relatively low, the restrictor 22 offers suificient resistance to properly'regulate refrigerant flow at the lower head m between-the condenser l4 and the evaporator 24 is that oifered by the restrictor 22.

. Thus, the present invention provides a means for varying the total restriction between the condenser andthe evaporator to produce the proper 55 resistance for any requirements of operation.

' While the form of embodiment of the invention as herein disclosed constitutes a preferred form, it is to be understood that other forms might be adopted, all coming within the scope of the 80 claims which follow.

What is claimed is as follows:

1. In a refrigerating apparatus, the combination of a compressor, a condenser, a fixed restrictor, an evaporator and conduit means there- 65 between forming a closed refrigerant circuit,

means interposed in the conduit means between said condenser and said fixed restrictor and forming a second restrictor, and a thermostatic device associated with said means and responsive 70 to changes in temperature of refrigerant flowing from said condenser through said means to said fixed restrictor in its passage through said conduit means to said evaporator for automatically varying the resistance of said second named restrictor.

2. In a refrigerating apparatus, the combination of a compressor, a condenser, a constantly open fixed restrictor, an, evaporator and conduit means therebetween forming a closed refrigerant circuit, means interposed in the conduit means 5 between saidcondenser and said constantly open fixed restrictor and forming a second restrictor,

and said second named restrictor being constantly open and also being variable in resistance automatically in response to changes in temper- 10 ature of refrigerant flowing from said condenser to said first named restrictor in its passage through said conduit means to said evaporator.

3. In a refrigerating apparatus, the combination f a compressor, a condenser, a constantly 15 open fixed restrictor, an evaporator and conduit means therebetween forming a closed refrigerant circuit, means interposed in the conduit means between said condenser and said constantly open fixed restrictor and forming a second restrictorfzo said second named restrictor being constantly open and also being variable in resistance automatically in response to changes in temperature of refrigerant flowing from said condenser to said first named restrictor in its 'passage 25 through said conduit means to said evaporator,

- and means disposed in said conduit means for interchanging heat between the refrigerant entering the evaporator and that leaving the evaporator.

4. In a refrigerating apparatus, the combination of a compressor,-a condenser, a constantly open fixed restrictor, an evaporator and conduit means therebetween forming a closed refrigerant circuit, means interposed in the conduit means between said condenser and said constantly open fixed restrictor and forming a second restrictor, said second named restrictor being constantly openand also being variable in resistance automatically in response to changes in temperature of refrigerant fiowing from said condenser to said first named restrictor in its passage through said conduit means to said'evaporator, means for interchanging heat between the refrigerant entering the evaporator and that leaving the evaporator, and said heat interchanging means being disposed in said conduit means extending from said second named restrictor to said first named restrictor.

5. In a refrigerating apparatus the combination of a compressor, a condenser, a constantly open fixed restrictor, an evaporator and conduit means therebetween forming a closed refrigerant circuit, means interposed in the conduit means between said condenser and said constantly open fixed restrictor and forming a second restrictor, said second named restrictor being constantly open and normally controlling the fiow of refrigerant from said condenser to said first named restrictor, and a thermostatic device associated with said second named restrictor and responsive to changes in temperature of refrigerant flowing therethrough to said first named restrictor for automatically varying the resistance of said second named restrictor to change the rate of fiow of refrigerant to said first named restrictor.

6. In a refrigerating apparatus the combination of a compressor, a. condenser, a constantly open fixed restrictor, an evaporator and conduit means therebetween forming a closed refrigerant circuit, means interposed in the conduit means between said condenser and said constantly open fixed restrictor and forming a second restrictor,

said second named restrictor being constantly means disposed in said conduit means for inter-- changing heat between the refrigerant entering the evaporator and that leaving the evaporator.

7. In a refrigerating apparatus the combination of a compressor, a condenser, a constantly open fixed restrictor, an evaporator and conduit means therebctween forming a closed refrigerant circuit, means interposed in-the conduit means between said condenser and said constantly open fixed restrictor and forming a second restrictor, said second named restrictor being constantly open and normally controlling the flow of refrigerant from said coridenser to said first named restrictor, a thermostatic device associated with said second named restrictor and responsive to changes in temperature of refrigerant flowing therethrough to said first named restrictor for automatically varying theresistance of said second named restrictor to change the rate of flow of refrigerant to said first named restrictor, means for interchanging heat between the refrigerant said evaporator, and means restricting means and operated in response to 25 entering the evaporator and that leaving the evaporator, and said heat interchanging means being disposed in said conduit means extending between said restrictors.

8. In a refrigerating apparatus, the combina- 5 ticn of a compressor, a condenser, an evaporator and conduits therebetween forming a closed refrigerant circuit, fixed restricting means interposed in the conduit between said condenser and said evaporator, and a thermostatically operated 10 device associated with said restricting means for by-passing refrigerant flowing from said condenser to said evaporator restricting means, said thermostatically operated device responding to an increase of temperature to increase the restrictive effect of said restricting means.

- 9. In a refrigerating apparatus, the combination of a compressor, a condenser, an evaporator and conduits therebetween forming a closed refrigerant circuit, fixed restricting means interposed in the conduit between said condenser and associated with said changes in temperature of refrigerant flowing from said condenser to said evaporator for bypassing reirigerant around a part of said restricting means.

FRANK F. STARR. 3

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